The present invention pertains to a color printer from which a single color, multi-color, or full color image may be obtained. More particularly, the present invention pertains to an advancement in the art of such printers which utilize image-wise exposure of a color forming layer of microcapsules to form a printed image.
In accordance with the prior art, a method of producing an image is known in which microcapsules, which encapsulate therein a photosensitive material, have been utilized in the formation of an image by image-wise exposure of the microcapsules to electromagnetic radiation. The photosensitive material encapsulated in these microcapsules has a viscosity which changes upon irradiation by electromagnetic radiation, usually of a specified wave length. It is also known to produce an image of two or more colors, or a full color image, by providing two or more types of microcapsules. Each type encapsulates a photosensitive material which has a change of viscosity in response to a specific wave length of electromagnetic radiation for its type, and has a chromogenic color forming material included within the microcapsule. Thus, upon image-wise exposure of a uniform layer of such microcapsules to radiation of the specific wave length, a latent image may be formed in the layer of microcapsules. This latent image is later developed by rupturing the microcapsules in which the photosensitive material has a low viscosity, so as to permit the chromogenic material to react with a developer to form the image. In the case of a full color image, three types of microcapsules are used, each type containing one of a cyan, magenta, or yellow chromogenic color forming compound.
The image-wise exposure of the microcapsule layer is accomplished using an irradiation source, such as a CRT, LCD, or the like. Alternatively, a reflective type irradiation source may be used in which a light source irradiates an original. The light irradiated onto the original is reflected from the surface thereof and is transmitted through a focusing lens to image-wise expose the microcapsule layer.
A latent image is thus formed in the microcapsules by the selective viscosity change in an internal phase of the microcapsule containing the chromogenic material. This viscosity change is due to the photosensitive material in the microcapsule being exposed to the electromagnetic radiation. The latent image is then developed by rupturing the microcapsules, usually using pressure rollers, so that the chromogenic material of selected microcapsules can come into contact with a developing agent. Thus, an observable image is formed. This image will invariably have a flat two dimensional surface structure.
The microcapsule layer is usually formed through electrostatic attraction of the microcapsules so that a uniform layer of microcapsules is indiscriminately disposed covering the entire printable surface of a support sheet. Such a conventional apparatus is disclosed in U.S. Pat. No. 4,801,949, issued to Misono, et. al.
An image recording apparatus which uses the image recording method described above is disclosed in U.S. Pat. No. 4,399,209, issued to Sanders et. al. This patent discloses in detail the structure of the microcapsules used in such a recording method and that explanation is incorporated herein by reference. It is also known to incorporate a ferromagnetic material within a microcapsule shell as is disclosed in U.S. Pat. No. 3,954,666, issued to Marquisee et. al., and insofar as this patent discloses the formation of a microcapsule, the constituents of the microcapsule shell and the ferromagnetic material encapsulated therein, this patent is incorporated herein by reference. Thermal expansive microcapsules are known in the art and are formed by encapsulating a low boiling, vaporizable substance into a microcapsule of a thermal plastic resin. U.S. Pat. No. 4,871,408, issued to Honma et. al. discloses such a thermal expansive microcapsule and is incorporated by reference herein. Furthermore, a heat meltable microcapsule is known in the art in which a heat meltable microcapsule has a capsule wall which includes infra-red absorbents which may absorb infra-red radiation at specific wave lengths to cause the heat meltable microcapsule to melt. U.S. Pat. No. 4,916,042, issued to Sakojiri, et. al. discloses such a microcapsule and its description is incorporated by reference herein.
Many drawbacks exist with the prior art printers which form a latent image in a microcapsule layer by image-wise exposure of electromagnetic radiation to the microcapsule layer. For example, there is no prior disclosure of a means for forming a three-dimensional topographical structure of an observable image by the selective build up of layers, having a varying thickness of microcapsules. Thus, there is no prior art which discloses such a structure. In fact, the only prior art which discloses a three-dimensional image is the Honma et. al. reference discussed above. However, in accordance with the teachings of Honma et. al., a uniform layer of thermal expansive microcapsules is formed, and then a toner image area is heated selectively so as to thermally expand the thermal expansive microcapsules in a selected region so as to raise the image.
Thus, there is no disclosure in the prior art of a color printer which is capable of producing an image having a topographical three-dimensional structure, such as to replicate the topographical three-dimensional structure of, for example, a conventionally painted painting. As shown in FIGS. 2(a) through 2(d), a conventional painting has an image which is formed by the application of paint using a conventional brush. The bristles of a conventional paint brush hold the paint so that when dragged across the surface of, for example, a portion of canvas, a brush stroke is left behind which has a topographical three-dimensional structure as shown in cross section in FIG. 2(c). This structure gives texture and expression to the painting which heretofore has been impossible to replicate using a microcapsule color printing method. Furthermore, there are many other instances where a three-dimensional printed structure is desirable, for example, the raised lettering of expensive letterhead or business cards. Conventionally, such raised lettering is very expensive and is only economical in large production lots. There is no known prior art which disclosed any means for obtaining such raised lettering using a microcapsule printer. Also, there is no prior art which discloses a means by which information pertaining to a desired image may be transmitted over data transmission lines, such as telephone lines, so that a desired three-dimensional structure may be obtained at a remote site.
There are input devices known in the art which provide the location of the input and the display of the inputted signals so as to be observable at the same location. Examples of such input devices are disclosed in U.S. Pat. No. 4,631,356, issued to Taguchi et. al., U.S. Pat. No. 4,771,276, issued to Parks, and U.S. Pat. No. 4,875,036, issued to Washizuka et. al. However, these prior art input devices do not disclose any means by which a brush stroke of a conventional brush may be replicated by such an input device so that the information pertaining to a topographical three-dimensional structure of such a brush stroke may be obtained to thereby replicate such a brush stroke using a microcapsule printer.